In an optical receiver that converts an optical signal into a voltage signal, when a photodetector (photodiode) outputs current, the output voltage of the optical receiver might be clipped by the bias current of the photodetector. To avoid this problem, a transimpedance amplifier (TIA) of the optical receiver requires a DC offset cancel (DCOC) function. At the same time, the amplifier also requires the function of current-based conversion of a single-phase signal into a differential signal.
To realize the aforementioned functions, various methods have been considered. Those methods, however, have the problems of increasing not only the area of the optical receiver but also the energy consumption.